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(a) AFM image of single-layer graphene. The folded edge exhibiting a relative height of z 4 A clearly indicates that it is a single-layer graphene. (b) TEM images of folded edges of single-layer and bi-layer graphenes. (c) High-resolution STM images of single-layer graphene. Optical microscope images of graphene crystallites on 300 nm SiO 2 imaged with (d) white light and (e) green light. The trace in (e) shows-step like changes in the contrast for single-, bi- and tri-layer graphenes. (Reproduced with permission from ref. 5, 11, 13 and 14).
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Graphene is a fascinating new nanocarbon possessing, single-, bi- or few- (≤ ten) layers of carbon atoms forming six-membered rings. Different types of graphene have been investigated by X-ray diffraction, atomic force microscopy, transmission electron microscopy, scanning tunneling microscopy and Raman spectroscopy. The extraordinary electronic pr...
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... reported to be formed by sonication in water following the chemical reduction of graphitic oxide with hydrazine. 10 Graphene has been characterized by employing microscopic and spectroscopic techniques. 1 Atomic force microscopy (AFM) is a basic characterization tool- which provides information of the number of graphene layers present in a sample (Fig. 2 a). 5 By differential height measurements at the folded edge, it is possible to obtain the layer thickness. In Fig. 2 a, the differential height is about 4 A, which is close to the thickness of a monolayer (3.4 A). Transmission elec- tron microscopy (TEM) provides infor- mation on the morphology and the number of layers (see Fig. 2 b). 11 ...
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... has been characterized by employing microscopic and spectroscopic techniques. 1 Atomic force microscopy (AFM) is a basic characterization tool- which provides information of the number of graphene layers present in a sample (Fig. 2 a). 5 By differential height measurements at the folded edge, it is possible to obtain the layer thickness. In Fig. 2 a, the differential height is about 4 A, which is close to the thickness of a monolayer (3.4 A). Transmission elec- tron microscopy (TEM) provides infor- mation on the morphology and the number of layers (see Fig. 2 b). 11 A folded graphene sheet is locally parallel to the electron beam. For single-layer graphene, a fold exhibits one ...
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... Fig. 2 a, the differential height is about 4 A, which is close to the thickness of a monolayer (3.4 A). Transmission elec- tron microscopy (TEM) provides infor- mation on the morphology and the number of layers (see Fig. 2 b). 11 A folded graphene sheet is locally parallel to the electron beam. ...
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... height is about 4 A, which is close to the thickness of a monolayer (3.4 A). Transmission elec- tron microscopy (TEM) provides infor- mation on the morphology and the number of layers (see Fig. 2 b). 11 A folded graphene sheet is locally parallel to the electron beam. For single-layer graphene, a fold exhibits one dark line (left panel in Fig. 2 b), similar to the TEM images from one-half of a single-walled carbon nano- tube. The right panel in Fig. 2 b shows a folded edge of bi-layer graphene, which exhibits two dark lines, similar to double- walled nanotubes. Direct imaging of lattice atoms and topological defects in single-layer graphene have been accom- plished by TEM by ...
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... microscopy (TEM) provides infor- mation on the morphology and the number of layers (see Fig. 2 b). 11 A folded graphene sheet is locally parallel to the electron beam. For single-layer graphene, a fold exhibits one dark line (left panel in Fig. 2 b), similar to the TEM images from one-half of a single-walled carbon nano- tube. The right panel in Fig. 2 b shows a folded edge of bi-layer graphene, which exhibits two dark lines, similar to double- walled nanotubes. Direct imaging of lattice atoms and topological defects in single-layer graphene have been accom- plished by TEM by using aberration correction in combination with a mono- chromator. 12 Fig. 2 c shows a high-reso- lution ...
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... carbon nano- tube. The right panel in Fig. 2 b shows a folded edge of bi-layer graphene, which exhibits two dark lines, similar to double- walled nanotubes. Direct imaging of lattice atoms and topological defects in single-layer graphene have been accom- plished by TEM by using aberration correction in combination with a mono- chromator. 12 Fig. 2 c shows a high-reso- lution scanning tunnelling microscope (STM) image of single-layer graphene over a 1 nm 2 area. 13 In the regions iden- tified as consisting of single-layer gra- phene, a honeycomb structure is observed. Searching for single-or bi-layer graphenes amongst millions of thicker flakes obtained by micromechanical ...
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... graphene becomes visible in an optical microscope if placed on top of a Si wafer with a 300 nm thick layer of SiO 2 . 5,14,15 Fig. 2 d and e show optical microscope images of graphene on 300 nm SiO 2 , imaged with white and green lights respectively. The trace in Fig. 2 e shows step-like changes in the contrast for single-, bi-and tri-layer graphenes. Only a 5% difference in the SiO 2 thickness can make graphene completely ...
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... graphene becomes visible in an optical microscope if placed on top of a Si wafer with a 300 nm thick layer of SiO 2 . 5,14,15 Fig. 2 d and e show optical microscope images of graphene on 300 nm SiO 2 , imaged with white and green lights respectively. The trace in Fig. 2 e shows step-like changes in the contrast for single-, bi-and tri-layer graphenes. Only a 5% difference in the SiO 2 thickness can make graphene completely ...
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... In Fig. 19 b, we show how the I 2D /I G ratio decreases markedly with the concentration of both TTF and TCNE. The I D /I G intensity ratio shows an opposite trend. This is because the origins of D and 2D bands are quite different. The electrical conductivity of graphene also varies on interaction with both electron-donor and -acceptor mole- cules (Fig. 20). Electron-donor molecules decrease the conductivity of graphene while electron-acceptor molecules increase the conductivity. Adsorption of H 2 O, NH 3 , CO, NO 2 and NO on gra- phene is also related to the charge-trans- fer between the molecules and the graphene surface. 60 The magnetic moment of molecules also seems to influence the ...
Citations
... Graphene, a two-dimensional material consisting of a single layer of carbon atoms, possesses unique physical features [10,11], such as high transmission [12], high thermal conductivity [13], and room-temperature ferromagnetism [14]. At the terahertz wave band, graphene can generate SPPs that are highly localized and low-loss [15][16][17][18]. ...
Graphene can support surface plasmon polaritons (SPPs) in the terahertz band, and graphene SPP sensors are widely used in the field of terahertz micro- and nano-optical devices. In this paper, we propose an H-shaped graphene metasurface and investigate the plasmon-induced transparency (PIT) phenomenon in the proposed structure using the finite-difference time-domain (FDTD) method. Our results show that the Fermi energy levels, as well as certain shape parameters, can effectively modulate the PIT phenomenon in the proposed structure. Interestingly, changing some of these shape parameters can excite two dips into three. In terms of sensing performance, the maximum values of sensitivity and figure of merit (FOM) are 1.4028 THz/RIU and 17.97, respectively. These results offer valuable guidance for the use of terahertz optical graphene SPP sensors.
... Graphene is a unique form of carbon which consists of carbon atoms bonded in six -member rings along a flat plane layer, and can consist of up to 10 such layers held together by electromagnetic forces [23]. Graphene family based layered nano materials include Graphene Oxide (GO), reduced graphene oxide (rGO), few layer graphene and ultra -thin graphene. ...
... Due to their high electrocatalytic activity for redox reactions, carbon-based nanomaterials (such as graphene) have been widely used for the simultaneous determination of DA and UA [14]. Graphene is an emerging two-dimensional (2D) honeycomb lattice carbonbased nanomaterial with excellent electrical conductivity, great chemical durability, a large specific surface area, superior thermal stability, a wide electrochemical window, and good biocompatibility [15][16][17][18][19]. The π-π stacking interactions between individual graphene sheets may lead to irreversible aggregation [20]. ...
Dopamine (DA) and uric acid (UA) are essential for many physiological processes in the human body. Abnormal levels of DA and UA can lead to multiple diseases, such as Parkinson’s disease and gout. In this work, a three-dimensional reduced graphene oxide–MXene (3D rGO-Ti3C2) composite electrode was prepared using a simple one-step hydrothermal reduction process, which could separate the oxidation potentials of DA and UA, enabling the simultaneous detection of DA and UA. The 3D rGO-Ti3C2 electrode exhibited excellent electrocatalytic activity towards both DA and UA. In 0.01 M PBS solution, the linear range of DA was 0.5–500 µM with a sensitivity of 0.74 µA·µM−1·cm−2 and a detection limit of 0.056 µM (S/N = 3), while the linear range of UA was 0.5–60 µM and 80–450 µM, with sensitivity of 2.96 and 0.81 µA·µM−1·cm−2, respectively, and a detection limit of 0.086 µM (S/N = 3). In 10% fetal bovine serum (FBS) solution, the linear range of DA was 0.5–500 µM with a sensitivity of 0.41 µA·µM−1·cm−2 and a detection limit of 0.091 µM (S/N = 3). The linear range of UA was 2–500 µM with a sensitivity of 0.11 µA·µM−1·cm−2 and a detection limit of 0.6 µM (S/N = 3). The modified electrode exhibited advantages such as high sensitivity, a strong anti-interference capability, and good repeatability. Furthermore, the modified electrode was successfully used for DA measurement in vivo. This could present a simple reliable route for neurotransmitter detection in neuroscience.
... Schematic illustration on the: (a) framework of graphite layers, (b) structure of graphene nanosheet, (c) the high-resolution picture displaying a pristine and flawlessly structured graphene sheet synthesized using the substrate-free gas-phase method. The individual carbon atoms are portrayed as white in this image, (d) electronic energy bands of a solitary layer of graphene nanosheet, and (e) out-plane π orbitals as well as in-plane σ bond perpendicular to the plane of the graphene nanosheet (Dato et al., 2009;Rao et al., 2009). ...
Multifunctional polymer networks fortified with the power of graphene and its derivatives as nano-inclusions have excellent sound absorption efficiency in broad frequency range, high loss factor, and matching impedance with that of water along with exceptional thermal, mechanical, and tribological properties are found to be the pre-eminent material for the underwater acoustic applications, particularly for the military tactics. To develop a stealthy underwater acoustic material, various factors need to be carefully considered, including matching acoustic impedance, glass transition temperature, loss factor, tan δ value, compression set and other mechanical properties, thermal stability, adhesion, and other tribological properties, which is briefly summarized in this review. Strategical development of hybrid nano-inclusions, viscoelastic polymer networks, nanocomposites as well as various interpenetrating polymer networks (IPNs), assiduous synthesis and surface modification of graphene are pivotal key approaches that need to be appraised. Simulation studies focusing on various potential models need to be developed for the feasibility studies and designing of the underwater acoustic material.
... In order to improve the activity of the catalyst and reduce the amount of noble metal used, scientists have tried to develop new carbon materials with good conductivity and high specific surface area, for example, carbon black (CB) [21][22][23], carbon nanotubes (CNT) [24][25][26], mesoporous carbon [27][28][29], etc. Due to the excellent performance of carbon materials, graphene aerogels (GA) born out of graphene materials have also attracted people's attention. Since the discovery of graphene in 2004, its extremely high specific surface area, single-atom thickness, and excellent physical and chemical properties have made graphene materials the best choice for anode catalysts in DMFCs [30][31][32][33][34][35][36]. However, the stacking of graphene sheets from the effect of van der Waals force hinders them to be used as good supports for fuel cells [37,38]. ...
Nowadays, two of the biggest obstacles restricting the further development of methanol fuel cells are excessive cost and insufficient catalytic activity of platinum-based catalysts. Herein, platinum nanoparticle supported graphene aerogel (Pt/3DGA) was successfully synthesized by a one-step hydrothermal self-assembly method. The loose three-dimensional structure of the aerogel is stabilized by a simple one-step method, which not only reduces cost compared to the freeze-drying technology, but also optimizes the loading method of nanoparticles. The prepared Pt/3DGA catalyst has a three-dimensional porous structure with a highly cross-linked, large specific surface area, even dispersion of Pt NPs and good electrical conductivity. It is worth noting that its catalytic activity is 438.4 mA/mg with long-term stability, which is consistent with the projected benefits of anodic catalytic systems in methanol fuel cells.. Our study provides an applicable method for synthesizing nano metal particles/graphene-based composites.
... [52] However, for larger widths, these properties are significantly influenced by the edge configurations. [53] While Geim and Novoselov's exfoliated graphene from graphite using scotch tape is not scalable, [54] chemical vapor deposition (CVD) synthesis of graphene, though well established, yields too low quantities (one sheet on the substrate), making it suitable for specific electronic or sensor applications rather than large-scale production. As a practical alternative, we can explore the viability of graphene oxide (GO), which can be produced in larger quantities. ...
Malaria is a major public health concern with over 200 million new cases annually, resulting in significant financial costs. Preventive measures and diagnostic remedies are crucial in saving lives from malaria, and especially in developing nations. 2D materials are, therefore, ideal for fighting such an epidemic. Graphene and its derivatives are extensively studied due to their exceptional properties in this case. The biomedical applications of graphene-based nanomaterials have gained significant interest in recent years due to their remarkable biocompatibility, solubility, and selectivity. Their unique physicochemical characteristics, like ample surface area, biofunctionality, high purity, solubility, substantial drug-loading capacity, and superior ability to penetrate cell membranes, make them up-and-coming candidates as biodelivery carriers. In this review, crucial graphene-based technologies to combat malaria are discussed. The advancements in preventing and diagnosing malaria and the biocompatibility of graphene-based nanomaterials are emphasized. The roadmap for using graphene-based technology toward achieving the WHO global malaria elimination by 2030 is presented and discussed in detail. Graphene oxide, the most critical biocompatible graphene derivative for health sensors, is also discussed. Additionally, 2D chalcogenides, specifically sulfide-based transition-metal dichalcogenides, are reviewed in detecting malaria during its early stages.
... As a result of this, the terahertz spectrum has found applications in a range of fields, including terahertz spectroscopy for agricultural product quality testing 6,7 , terahertz sensing 8 , and terahertz imaging 9 . Graphene, a two-dimensional material consisting of a single layer of carbon atoms, possesses unique physical features 10,11 , such as high transmittance 12 , high thermal conductivity 13 and room-temperature ferromagnetism 14 . At terahertz wave band, graphene can generate SPPs that are highly localised and low-loss [15][16][17] . ...
Graphene can support surface plasmon polaritons (SPPs) in terahertz band and the graphene SPPs sensors are widely used in the field of terahertz micro- and nano-optical devices. In this paper, we propose an H-shaped graphene metasurface and use finite-difference time-domain (FDTD) method to investigate its generated plasmon-induced transparency (PIT) phenomenon. Our results show that the Fermi energy levels, as well as the certain shape parameters, can effectively modulate the PIT phenomenon of the proposed structure. Interestingly, changing some of these shape parameters can excite two dips into three. In terms of sensing performance, the maximum values of sensitivity and figure of merit (FOM) are 1.4028 THz/RIU and 17.97, respectively. These findings offer valuable guidance for the use of terahertz micro-nano optical graphene SPPs sensors.
... A novel nanocarbon known as graphene is a 2D product composed of single-, bi-, or few-(≤10) layers of C atoms arranged in six-membered rings. [124] Graphene is a single sheet of graphite with sp 2 hybridized C atoms organized in a honeycomb lattice structure. It possesses outstanding properties like great mechanical strength, great electrical conductance, chemical stability, and increased surface area. ...
The rise in universal population and accompanying demands have directed towards an exponential surge in the generation of polymeric waste. The estimate predicts that world‐wide plastic production will rise to approximately 590 million metric tons by 2050, whereas 5000 million more tires will be routinely abandoned by 2030. Handling this waste and its detrimental consequences on the Earth's ecosystem and human health presents a significant challenge. Converting the wastes into carbon‐based functional materials viz. activated carbon, graphene, and nanotubes is considered the most scientific and adaptable method. Herein, we provide an overview of the various sources of polymeric wastes, modes of build‐up, impact on the environment, and management approaches. Update on advances and novel modifications made in methodologies for converting diverse types of polymeric wastes into carbon nanomaterials over the last five years are given. A remarkable focus has been made to comprehend the applications of polymeric waste derived carbon nanomaterials (PWDCNMs) in the CO 2 capture, removal of heavy metal ions, supercapacitor‐based energy storage and water splitting with an emphasis on the correlation between PWDCNMs' properties and their performances. This review offers insights into emerging developments in the upcycling of polymeric wastes and their applications in environment and energy.
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... Graphene, a 2D material of a single layer composed of carbon atoms organized in a hexagonal lattice, plays a significant role in the field of energy materials owing to their exceptional properties (Javed et al., 2022). One of the most extraordinary properties of graphene is its high electrical conductivity, which is much higher than the conductivity of conventional electronic materials, such as silicon (Rao et al., 2009). Because of this feature, graphene is ideally suitable for use in a wide variety of electronic devices, including batteries, supercapacitors, and other energy storage systems, in which effective electron mobility is crucial for obtaining the highest performance level. ...
... erative braking systems in electric vehicles (Rao et al., 2009). Moreover, graphene has better thermal conductivity and extraordinary electrical conductivity. ...
The study of two-dimensional materials, often known as 2D materials, has seen remarkable advancements in recent decades. The study of 2D nanomaterials has received a significant amount of interest due to the extraordinary properties of these materials, which include outstanding physicochemical properties, optical behavior, electrical conductivity, thermoelectric properties, and mechanical strength. These unique properties make 2D nanomaterials promising candidates for various applications in fields, such as electronics, energy storage, catalysis, and biomedicine. Additionally, the ability to manipulate and control the properties of 2D nanomaterials at the atomic level has opened new possibilities for designing and engineering novel materials with tailored functionalities of electrical and mechanical characteristics. In addition, 2D materials have properties that are more conductive when compared to their bulk structures. The 2D nanomaterials have attracted a lot of attention in a variety of sectors, particularly in the fields of energy, hydrogen generation, and gas retention, because of their one-of-a-kind properties. The primary purpose of this chapter is to provide a detailed explanation of the fundamental concepts that serve as the foundation for the prominent properties that 2D materials exhibit. In addition, an overview as well as a detailed examination of numerous categories of 2D nanomaterials, such as graphene, and MXene. This chapter also offers a comprehensive review of a variety of synthesis procedures as well as strategies that can be utilized for the purpose of characterizing and synthesizing 2D nanomaterials. In addition, there are applications in the field of energy storage and devices that convert energy, such as batteries, solar cells, and supercapacitors.
... Graphene oxide (GO) is a quasi-two-dimensional lamellar nanomaterial whose molecular structure is shown in Figure 1. Owing to its unique two-dimensional honeycomb lattice structure with extended π bond conjugation, GO exhibits excellent mechanical, thermal, and electrical properties, and it can significantly improve the toughness, thermal resistance, and mechanical properties of EPs [10,11]. However, due to the strong hydrogen bonding and the dipole force of oxygen-containing groups between the GO layers, irreversible aggregation is prone to occur, seriously affecting its dispersion performance in EPs. ...
Phenyl polyhedral oligomeric silsesquioxane (POSS) is modified onto the GO surface by using the strong π–π coupling between a large number of benzene rings at the end of the phenyl POSS structure and the graphite structure in the GO sheet, realizing the non-covalent functionalization of GO (POSS-GO). The POSS-GO-reinforced EP (POSS-GO/EP) composite material is prepared using the casting molding process. The surface morphology of GO before and after modification and its peel dispersion in EP are examined. Furthermore, the mechanical properties, cross-sectional morphology, and reinforcement mechanism of POSS-GO/EP are thoroughly examined. The results show that the cage-like skeleton structure of POSS is embedded between the GO layers, increasing the spacing between the GO layers and leading to a steric hindrance effect, which effectively prevents their stacking and aggregation and improves the dispersion performance of GO. In particular, the 0.4 phr POSS-GO/EP sample shows the best mechanical properties. This is because, on the one hand, POSS-GO is uniformly dispersed in the EP matrix, which can more efficiently induce crack deflection and bifurcation and can also cause certain plastic deformations in the EP matrix. On the other hand, the POSS-GO/EP fracture cross-section with a stepped morphology of interlaced “canine teeth” shape is rougher and more uneven, leading to more complex crack propagation paths and greater energy consumption. Moreover, the mechanical meshing effect between the rough POSS-GO surface and the EP matrix is stronger, which is conducive to the transfer of interfacial stress and the strengthening and toughening effects of POSS-GO.
